This is definitely an interesting result and worth following up but rather than declare victory the real question is why is there such a large discrepancy with other data? A factor of two is nothing to quibble over. This is astronomy for god's sake!
Graphene: the 2D hexagonal carbon lattice made in every pencil scratching... boring, right? It seems everyone, myself included, in Condensed Matter (Solid State) Physics is working on this one. It's like high-Tc superconductivity, very promising. Unlike that field, however, it's open to much more reliable experiments and slightly simpler theory. The upload rate on arxiv is over 1 paper/day on this material*.
The key to graphene (from a theoretical standpoint) is that its band structure is gapless and electrons (ok, quasi-electrons) are massless, moving at ~10^6 m/s! Normal (Si-based, GaAs,...) semiconductors are gapped, meaning there is some energy associated with the valence and conduction bands and there is an energy gap between them. Experimentally we can control certain parameters (doping, primarily) to change electron/hole occupation of the bands and thus make things like p/n junctions, transistors and so on. With graphene, there's no gap. On one hand, this means ballistic transport is approximately possible. Graphene has a ridiculously high mobility (ludicrous speed even). However, we need to come up with tricks to make it into traditional electronics. Ribbons are one approach. The edges break rotational symmetry and give rise to edge states, which can be manipulated to create a gap. Some other types of topological defects can do it too. There are probably over 1000 papers on the subject and in some sense the field is less than 5 years old. I'm glad to see the recognition this is getting and hopefully we'll be a part of some new groundbreaking tech.
*I'm currently working on a pretty interesting theory which may or may not solve the switching issue mentioned in the article; alas, the proof is too small to fit in the margins of this post!
From reading the original paper (circa 2000) the parent is correct.
They use CUE (the Circular Unitary Ensemble on, you guessed it, unitary NxN random matrices) to define an f(n) which is the product (from j=0 to n-1) of j!/(j+n)!.
Then a(n), which they call N, is the moment of the Riemann zeta. Conveniently, a(n) = N = f(n)*(n^2)! So write a dozen line program, and you too can compute these values.
a(1) = 1 a(2) = 2 a(3) = 42 a(4) = 24024
and so on...
They show the theory is in excellent agreement with statistical results of the first 10^20th zeros of the Riemann zeta.
The major innovation you get by using sound is that your detector can be smaller (i.e. faster) and less reliant on precise optics. This is the double whammy Grail of nano-imaging.
From TFA:
"For a regular AFM to detect the features of the object, the actuator must be large enough to move the cantilever up and down. The inertia of this large actuator limits the scanning speed of the current AFM. But FIRAT solves this problem by combining the actuator and the probe..."
But there seems to be some discrepancy in the article.
"Georgia Tech researchers have been able to use FIRAT with a commercial AFM system to produce clear scans of nanoscale features at speeds as high as 60 Hertz (or 60 lines per second)."
Is this what they mean by a "movie" which they claim has never been done with AFMs? It's true that commercial AFMs do not achieve this speed, but http://hansmalab.physics.ucsb.edu/index.html/ for example custom builds AFMs to that spec since 2002.
The second part that seems misinformed is that FIRAT is not unique in it's use of surface properties and a cantilever-type system. Current AFMs "bounce" off the surface in the same way, interacting well before actual contact (insofar as contact has meaning in the quantum mechanical sense).
At the risk of trolling beyond my bounds...
It irks me to hear a good joke all the way to the end, only to find someone botched the punchline. Thank you fellow mathematician for enlightening us to the real deal.
Just so this isn't a pure fluff-post, here's a link to the abstract of the original paper from clinical studies in mice, published in Physical Review Letters, June 7, 2004. Mind you this has only been tested in one human case study and they make no claims to generalize this to other forms of cancer.
Slashdot Mirror
Graphene: the 2D hexagonal carbon lattice made in every pencil scratching... boring, right? It seems everyone, myself included, in Condensed Matter (Solid State) Physics is working on this one. It's like high-Tc superconductivity, very promising. Unlike that field, however, it's open to much more reliable experiments and slightly simpler theory. The upload rate on arxiv is over 1 paper/day on this material*.
...) semiconductors are gapped, meaning there is some energy associated with the valence and conduction bands and there is an energy gap between them. Experimentally we can control certain parameters (doping, primarily) to change electron/hole occupation of the bands and thus make things like p/n junctions, transistors and so on. With graphene, there's no gap. On one hand, this means ballistic transport is approximately possible. Graphene has a ridiculously high mobility (ludicrous speed even). However, we need to come up with tricks to make it into traditional electronics. Ribbons are one approach. The edges break rotational symmetry and give rise to edge states, which can be manipulated to create a gap. Some other types of topological defects can do it too. There are probably over 1000 papers on the subject and in some sense the field is less than 5 years old. I'm glad to see the recognition this is getting and hopefully we'll be a part of some new groundbreaking tech.
The key to graphene (from a theoretical standpoint) is that its band structure is gapless and electrons (ok, quasi-electrons) are massless, moving at ~10^6 m/s! Normal (Si-based, GaAs,
*I'm currently working on a pretty interesting theory which may or may not solve the switching issue mentioned in the article; alas, the proof is too small to fit in the margins of this post!
http://www.hpl.hp.com/techreports/2000/HPL-BRIMS-2 000-02.html
From reading the original paper (circa 2000) the parent is correct.
They use CUE (the Circular Unitary Ensemble on, you guessed it, unitary NxN random matrices) to define an f(n) which is the product (from j=0 to n-1) of j!/(j+n)!.
Then a(n), which they call N, is the moment of the Riemann zeta.
Conveniently, a(n) = N = f(n)*(n^2)! So write a dozen line program, and you too can compute these values.
a(1) = 1
a(2) = 2
a(3) = 42
a(4) = 24024
and so on...
They show the theory is in excellent agreement with statistical results of the first 10^20th zeros of the Riemann zeta.
The major innovation you get by using sound is that your detector can be smaller (i.e. faster) and less reliant on precise optics. This is the double whammy Grail of nano-imaging. From TFA: "For a regular AFM to detect the features of the object, the actuator must be large enough to move the cantilever up and down. The inertia of this large actuator limits the scanning speed of the current AFM. But FIRAT solves this problem by combining the actuator and the probe..." But there seems to be some discrepancy in the article. "Georgia Tech researchers have been able to use FIRAT with a commercial AFM system to produce clear scans of nanoscale features at speeds as high as 60 Hertz (or 60 lines per second)." Is this what they mean by a "movie" which they claim has never been done with AFMs? It's true that commercial AFMs do not achieve this speed, but http://hansmalab.physics.ucsb.edu/index.html/ for example custom builds AFMs to that spec since 2002. The second part that seems misinformed is that FIRAT is not unique in it's use of surface properties and a cantilever-type system. Current AFMs "bounce" off the surface in the same way, interacting well before actual contact (insofar as contact has meaning in the quantum mechanical sense).
Namely, "Genius loves company".
IBM ftw.
At the risk of trolling beyond my bounds...
It irks me to hear a good joke all the way to the end, only to find someone botched the punchline. Thank you fellow mathematician for enlightening us to the real deal.
Just so this isn't a pure fluff-post, here's a link to the abstract of the original paper from clinical studies in mice, published in Physical Review Letters, June 7, 2004. Mind you this has only been tested in one human case study and they make no claims to generalize this to other forms of cancer.
http://scitation.aip.org/getabs/servlet/GetabsSer
I will most likely download the full report tomorrow from the university.